Release Date:  April 4, 2005        Contact:  Craig A. Creaturo
                                              Chief Financial
                                              Officer and Treasurer
                                              (724) 352-4455
                                              ccreaturo@ii-vi.com
                                              Homepage:  www.ii-vi.com





               II-VI INCORPORATED, SEMISOUTH LABORATORIES, INC.
               AND MISSISSIPPI STATE UNIVERSITY PARTNER IN THE
                       DEVELOPMENT OF SILICON CARBIDE

PITTSBURGH, PA., April 4, 2005  -- II-VI Incorporated (NASDAQ NMS: IIVI)
announced today that it is partnering with SemiSouth Laboratories, Inc.
and Mississippi State University for the establishment of a Silicon
Carbide (SiC) semiconductor substrate manufacturing facility in
Starkville, Mississippi.  This effort will focus on II-VI's production
capabilities in SiC substrates along with an advanced SiC epitaxial
material growth technology at SemiSouth.  During this process, strong
technical and operational support will be provided from II-VI's New
Jersey-based Wide Bandgap Materials Group Technical Center and
Headquarters where II-VI will strengthen its research and worldwide
marketing.

Earlier today, Carl J. Johnson, chairman and chief executive officer of
II-VI Incorporated noted the following during a visit to Mississippi.
"Our technology and manufacturing development teams in New Jersey and
Pennsylvania have made considerable advancements in the growth of single
crystal SiC materials.  Anticipating continued success and market growth,
we are now entering a new phase of our business as we prepare for the
scale-up to high volume production.  II-VI is looking forward to
partnering with Mississippi State University and SemiSouth in this highly
productive initiative."

II-VI Incorporated also announced that it made an investment in
SemiSouth. Terms of the transaction were not disclosed.

Headquartered in Saxonburg, Pennsylvania, II-VI Incorporated designs,
manufactures and markets optical and opto-electronic components, devices
and materials for infrared, near-infrared, visible light, x-ray and gamma
ray instrumentation.  The Company's infrared optics business manufactures
optical and opto-electronic components sold under the II-VI brand name
and used primarily in CO2 lasers.  The Company's near-infrared optics
business manufactures near-infrared and visible light products for
industrial, scientific, military and medical instruments and laser gain
materials and products for solid-state YAG and YLF lasers at the
Company's VLOC subsidiary.  The Company's military infrared optics
business manufactures infrared products for military applications under
the Exotic Electro-Optics (EEO) brand name.  In the Company's Compound
Semiconductor Group, the eV PRODUCTS division manufactures and markets
solid-state x-ray and gamma-ray sensor products and materials for use in
medical, industrial, environmental, scientific and homeland security
applications; the Company's Wide Bandgap Materials (WBG) group
manufactures and markets single crystal silicon carbide substrates for
use in the solid-state lighting, wireless infrastructure, RF electronics
and power switching industries; Marlow Industries, Inc. designs and
manufacturers thermoelectric cooling and power generation solutions for
use in defense, space, photonics, telecommunications, medical, consumer
and industrial markets.

This press release contains forward-looking statements based on certain
assumptions and contingencies that involve risks and uncertainties.  The
forward-looking statements are made pursuant to the safe harbor
provisions of the Private Securities Litigation Reform Act of 1995 and
relate to the Company's performance on a going-forward basis.  The
forward-looking statements in this press release involve risks and
uncertainties, which could cause actual results, performance or trends,
including the above mentioned anticipated revenues and earnings, to
differ materially from those expressed in the forward-looking statements
herein or in previous disclosures.  The Company believes that all
forward-looking statements made by it have a reasonable basis, but there
can be no assurance that management's expectations, beliefs or
projections as expressed in the forward-looking statements will actually
occur or prove to be correct.  In addition to general industry and
economic conditions, factors that could cause actual results to differ
materially from those discussed in the forward-looking statements in this
press release include, but are not limited to: (i) the Company's ability
to successfully integrate Marlow's operations into the Company's
organization and to realize synergies in material growth and utilization
of our worldwide manufacturing and distribution networks (ii) the failure
of any one or more of the assumptions stated above to prove to be
correct; (iii) the risks relating to forward-looking statements and other
"Risk Factors" discussed in the Company's Annual Report on Form 10-K for
the fiscal year ended June 30, 2004; (iv) purchasing patterns from
customers and end-users; (v) timely release of new products, and
acceptance of such new products by the market; (vi) the introduction of
new products by competitors and other competitive responses; and/or (vii)
the Company's ability to devise and execute strategies to respond to
market conditions.

CONTACT:  Craig A. Creaturo, Chief Financial Officer and Treasurer of II-
VI Incorporated, 724-352-4455, or e-mail, ccreaturo@ii-vi.com.

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